Does fire influence phosphite protection of Western Australian indigenous plant species against Phytophthora cinnamomi?

Large areas of indigenous forests, and Banksia woodlands and heathlands in Australia are devastated by Phytophthora dieback caused by P. cinnamomi. Phosphite has been shown to be effective in controlling this pathogen on a wide range of plant species across different families. Although fire is a regular event in the Australian landscape and plays key roles in the ecosystem, nothing is known about the relative uptake of phosphite by shoots pre- and post-fire or how fire may alter the redistribution and persistence of phosphite within woody plants. Adenanthos cuneatus (re-sprouter), Banksia attenuata (re-sprouter) and B. baueri (re-seeder) are all susceptible to P. cinnamomi and are responsive to phosphite treatment. These species were selected within four plots in an area of the Stirling Range National Park that was scheduled for a fuel-reduction burn in November 2006. Treatments of the plots were: 1) phosphite spray without fire, 2) phosphite spray with fire, 3) no phosphite spray without fire, and 4) no phosphite spray with fire. A phosphite treatment was applied either 6 weeks pre-fire or 9 months post-fire when all re-sprouter species had sufficient foliage. Leaf water potentials, leaf gas exchange, lesion lengths on inoculated stems, and phosphite concentration in leaves, stems, lignotubers and roots measured periodically throughout the experiment will be presented